well

Well no, they only faint.

If you don't take care of your Sim, like starve them or not taking their showers daily
[basicly, when your Sim is unhappy] then they faint.

Now here's a problem to this, if you only have one Sim in that house or is at the moment,
then you have to wait for the peramedic to come and revieve your Sim. But if it's not the
only one at the moment or if you have more then one Sim at the time then take another Sim
and revieve the onther one.

Now just remember this: no matter how many times this all happens, your Sims will NEVER
die.

With pets it goes for the same thing, if they faint you revieve them or the peramedic does
and they will NEVER die.

BUT... if this happens too many times your pet might and WILL leave you for not taking
care of him/her. So if your pet suggests in your relation with him/her that your not
his/her mistress or master with ANY Sim, you might not be able to own your pet anymore
[unlesss it's the opposite, that you do own the pet, then everything will be ok].